As local area network (LAN) and wide area network (WAN) topologies become more complex, network management tools become critically important. As is known to those skilled in the art, the Simple Network Management Protocol (“SNMP”) is one currently popular example of a network management tool. SNMP provides a systematic way of monitoring and managing a computer network and has become the standard in network management. The SNMP model of a managed network includes four types of components: (1) managed nodes or network elements, (2) management stations, (3) management information, and (4) a management protocol. The managed nodes can be hosts, routers, bridges, printers, or any other devices capable of communicating status information to the management stations. Management stations monitor and manage the devices on the network. The management information contains information on the components of the network and the management protocol is the format in which this information is communicated to the management system. The CiscoWorks™ software package, available from Cisco Systems, Inc. of San Jose, Calif., is an example of network management product supporting SNMP.
Many networks contain components manufactured by several different companies. In order for the management station to communicate effectively with these varied devices, the nature of the information maintained by the agents must be rigidly specified. SNMP therefore describes the exact information each agent must maintain and the format in which it must be maintained in data structures called management information bases (MIB).
A MIB is a local database of variables that may describe the current and past state of the node to which it is assigned as well as instructions affecting the operation of the node. Network management is then carried out by the management stations. The management stations have one or more processes that communicate with the SNMP agents through the network by issuing commands and getting responses. One of the advantages of this design is that much of the complexity of the system is located in the management stations, rather than in the SNMP agents, allowing the agents to be as simple as possible to minimize their effect on the nodes on which they are running.
Data communications networks are widespread and there are many different types of networks, including LANs (Local Area Networks), MANs (Metropolitan Area Networks), and WANs (Wide Area Networks). They are used for providing numerous services, both for companies and for individuals. They provide a powerful communication mechanism and allow access to various kinds of remote information. Two or more networks connected together form an internetwork (or internet). The “Internet” is a worldwide internet widely used to connect universities, government offices, companies, and private individuals. Every host (or end-user's machine running user applications) and router interface on the Internet has an Internet Protocol (IP) address, which encodes its network number and host number. IP addresses are typically 32 bits long and are used in the source address and destination address fields of IP packets. The Source Address is the ultimate source of the IP packet; the Destination Address is the ultimate destination of the IP packet.
FIG. 1 illustrates IP address formats well known to those of ordinary skill in the art. The IP address formats are divided into five classes. The class A format 100, which begins with a “0” bit 102 for indicating the class and has a 7-bit network address field 105 and a 24-bit host address field 110, allows up to 126 networks with 16 million hosts each. The class B format 115 beginning with the bit pattern “10” 120 allows 16,382 networks with up to 64K hosts each. The class C format 125 beginning with the bit pattern “110” 130 allows 2 million networks (e.g., LANs) with up to 254 hosts each. The class D format 135 beginning with “1110” 140 is for multicast in which a packet is directed to multiple hosts. Finally, the Class E format 145 beginning with the bit pattern “11110” 150 is reserved for future use. Network numbers are assigned by the InterNIC (Internet Network Information Center) or another administrative body in order to avoid conflicts.
The growth of the Internet appears to be exponential. Tens of thousands of networks are now connected to the Internet, and the number is close to doubling every year. Unfortunately, however, IP addresses are not infinite and it is rather expensive to procure more IP addresses. With the increase in the number of users of the Internet, Telcos (Telecommunication companies) and ISPs (Internet Service Providers) are faced with an increasing shortage of IP addresses.
The network edge is the point where customer traffic enters a service provider's network. Traffic can arrive at the edge via access technologies including dial, IP, ATM, Frame Relay, leased line, wireless, Digital Subscriber Line (xDSL) and cable. An edge switch or edge router aggregates traffic from all or some of these access interfaces, and forwards packets over a multiplexed packet network core.
FIG. 2 depicts an exemplary network edge. DSL access multiplexer 200 terminates and aggregates DSL connections 205, 210, 215. Router 220 aggregates leased lines 225, 230. Cable modem termination system (CMTS) 235 terminates and aggregates cable modem connections 240, 245. Media gateway 250 translates PSTN 255 traffic into packets. Network edge 260 may also contain multiservice switches (not shown in FIG. 2) for delivering services including Frame Relay, leased lines, ATM, IP and voice. Packets from network edge devices 202, 220, 235, 250 are forwarded over packet network core 260.
IP pools 212, 232, 242 and 252 are typically utilized on network edge devices 202, 220, 235, 250 to hold a pool of addresses that can be used for dynamic address assignment for PPP sessions as they are terminated on edge aggregation devices 202, 220, 235, 250. Frequently, several network edge devices must share a single IP address space. Consequently, the addresses must be divided amongst the edge termination devices 202, 220, 235, 250. Currently, IP addresses are allocated in a manual fashion. One or more individuals 265, 270, 275, 280 assign a range of IP addresses to each device 202, 220, 235, 250. Scripts are used to periodically review IP address usage to determine whether efficient use is being made of the IP address space allocated to edge termination devices 202, 220, 235, 250. Address ranges are reallocated when individuals 265, 270, 275, 280 determine that more efficient use can be made of the IP address space. Unfortunately, the dynamic nature of IP address requests complicates IP address management. Improper management of IP address pools can result in IP address pool depletion and the subsequent denial of service.
The currently available solutions to this problem are very limited and do not offer the level of service that most subscribers demand. One solution places global IP address information in an authentication, authorization and accounting (AAA) server. However, this solution is inadequate because if an AAA server goes down, IP address information may be lost.
What is needed is a solution that provides relatively efficient and reliable management of network edge device IP address pools, such that subscriber denial of service is minimized. A further need exists for such a solution that is relatively easy to implement.